Richard Gill, Biology
Evaluation of how well the academic objectives of the proposal were met
The central aim of this proposal is to provide opportunities for students from diverse academic backgrounds to work collaboratively on a number of federally funded environmental change experiments across four of Utah’s ecosystems—Mojave Desert, Great Basin Shrub Steppe, Subalpine Tall Forb, and Colorado Plateau Grassland. This proposal funded 4 students from life sciences and engineering.
In 2012 and 2013 these students collected data on plant and soil responses to altered weather conditions. Students worked collaboratively on expanding a sensor network at both desert and mountain ecosystems. This work was so effective that we got an in-‐kind grant from a sensor company to install their first wireless sensor network in a large-‐scale ecological experiment. As a result of this work, we have two manuscripts from our montane work in review and an additional four in preparation from our desert work that will be submitted within the next six months.
Evaluation of the mentoring environment
The mentoring environment and plan focus on allowing students with diverse interests and training to work together on complex problems with frequent interaction with faculty and graduate students. This model of cooperative, community-‐centered learning is consistent with learning theory. The National Research Council’s report on student learning emphasized that developing into an expert requires, among other things, (1) using initial understanding to frame new concepts and (2) the ability to transfer knowledge from one realm into another. Our “community of learners” approach to this project used both of these approaches. We emploedy the diverse initial understanding in interests possessed by students of different majors to engage in the concepts unique to the specific aims of this project. In addition, because there is a strong interdependence among the students, requiring them to transfer their knowledge to meet each other’s needs and will benefit from the perspectives of other students.
Students supported have made presentations at national scientific meetings and are preparing manuscripts based on data that they have collected. We had weekly group meetings to discuss data and read current literature. One modification that we made to the initial plan was to link our weekly meetings with those conducted by Sam St. Clair, further modeling interdisciplinary work. In addition, I have weekly meetings with the undergraduates who are actively analyzing data and preparing manuscripts.
List of students who participated and what academic deliverables they have produced or it is anticipated they will produce
Lafe Conner, PhD Student
- Conner, LG, M.C. Bunnell, RA Gill. 2014 Forest diversity and patterns of spruce survival following a spruce beetle epidemic. Canadian Journal of Forest Research 44(11): 1369-‐1375, 10.1139/cjfr-‐2014-‐0236
- Conner, Lafe G., Ames, Daniel P., Gill, Richard A., (2013) HydroServer Lite as an Open Source Solution for Archiving and Sharing Environmental Data for Independent University Labs, Ecological Informatics, doi:10.1016/j.ecoinf.2013.08.006.
- LG Conner, RA Gill, R O’Connor. 2013. Connecting to the data-‐intensive future of scientific research. NASA Space Grant Meeting, SLC
- Conner, LG, RA Gill. 2014. Effects of dust-‐caused early snowmelt on soil moisture, soil carbon and nitrogen, and plant growth and reproductive output in a snow manipulation experiment. American Geophysical Meeting, San Francisco.
- Conner, LG and RA Gill. In Review The effect of dust-‐caused early snowmelt on flowering phenology, growth, and seed-‐set of Erythronium grandiflorum (Glacier Lily; Liliaceae) in a snow manipulation experiment. American Journal of Botany
Rory O’Connor, MS StudentH
- Rory C. O’Connor*, Samuel B. StClair, Richard A. Gill. 2014. SHIFTS IN PLANT COMMUNITY REESTABLISHMENT POST-‐FIRE DUE TO SMALL MAMMALS. Society for Range Management Meeting, Orlando, FL. Poster Presentation.
- RC O’Connor. 2014. Small Mammals Matter? Linking Plant Invasion, Biotic Resistance, and Climate Change in Post-‐Fire Plant Communities. M.S. Thesis.
Michael C. Bunnell, Undergraduate Student/Newly enrolled MS Student
- Conner, LG, M.C. Bunnell, RA Gill. 2014 Forest diversity and patterns of spruce survival following a spruce beetle epidemic. Canadian Journal of Forest Research 44(11): 1369-‐1375, 10.1139/cjfr-‐2014-‐0236
- Bunnell, MC. 2014. Sapflux measurements of landscape trees in Heber Valley, UT. iUtah All Hands Meeting, Logan, UT.
Allison Shumway, Beau Walker, Sarah Karlinsey, David Robinson. Undergraduate Students
- Gill, RA, CS Campbell, AO Shumway, BJ Walker, SM Karlinsey, D Robinson. In Revision. Soil moisture controls Engelmann Spruce (Picea engelmannii) seedling carbon balance and survivorship at treeline. Functional Ecology
Josh Harvey, Undergraduate Student
- Harvey, Josh. 2014. Seasonal water availability and temperature drive subalpine carbon soil flux. Utah Conference on Undergraduate Research.
Description of the results/findings of the project
Desert Rainout Experiment
Bottom-‐up and top-‐down effects are two explanations for how plants establish in dryland ecosystems. These two paradigms tend to be acknowledged separately and rarely combined to describe invasive species establishment. In the Mojave Desert Bromus rubens is altering the native plant community by shortening the fire return intervals. We implemented a nested full factorial experiment that observes how B. rubens establishes under different precipitation regimes and how small mammal predation affects its establishment in burned and intact plant communities. For two growing seasons we monitored B. rubens density (m-‐2), biomass (g m-‐ 2), and seed density (m-‐2). We observed that small mammals do create a top-‐down pressure on B. rubens’ establishment in both burned and intact plant communities. The greatest effect of small mammals is during years of average precipitation where they reduce up to 50% of B. rubens’ density. During droughts and severe droughts their top-‐down effects are negligible. As a result precipitation creates a threshold below which the efficacy of small mammal herbivory is not observed. Thus there is a tight relationship between top-‐down and bottom-‐up effects in dryland ecosystems where both have significant intertwined effects on exotic plant establishment.
Montane Snow Manipulation Study
Regional climate forecasts for the western United States predict slightly more snow accumulation during the winter but warmer springs and earlier spring snowmelt. Snowmelt will be further advanced by radiative forcing from dust and black carbon deposition on mountain snowpack. We expect earlier snowmelt to reduce regional water supplies and suspect that it may also lead to drier soil conditions which could impact nutrient cycling and plant growth and reproduction in alpine and subalpine environments. Our snow manipulation experiment included 12 sites at two elevations in paired forest and meadow sites. We added dust to the snow surface during spring ablation. The dust treatment reduced snowpack by 20 to 40% and advanced the snowfree date by 9 to 14 days. Following snowmelt, there was a temporary difference in soil moisture in the upper 0-‐15 cm of soil between the treatment and control plots. Following snowmelt, the temporary differences in soil moisture quickly converged during soil drydown to a lower limit determined by the soil characteristics specific to each site. This brief window of differences in soil moisture may have temporary impacts on ecosystem processes; however, the impacts are mediated by plant and microbial phenology. Some of the plants and microbes in seasonally-‐snow-‐covered environments are adapted to take advantage of the early season environments which include low temperatures and frequent freezing, while other plants and microbes have evolved to avoid this transition period through prolonged dormancy. These adaptations, and the transient nature of environmental differences caused by early snowmelt, may limit the impacts of early snowmelt on carbon and nitrogen cycling and on plant growth and reproduction in subalpine forest and meadows.
Montane Rain Manipulation Study
- Most hypotheses about controls over upper treeline suggest that low temperature drives treeline position, either through direct effects on cell division and tree growth or through indirect effects due to frost damage or nutrient availability. Support for these hypotheses is apparent in the increase in nonstructural carbohydrates in conifer needles from intact forest to timberline. Also, over 50% of treelines have increased in elevation in the past century as temperatures have increased. However, abiotic factors other than temperature, including nitrogen or water availability, may serve as another important controls over treeline, particularly for seedlings.
- To test the hypothesis that the timing and amount of precipitation exerts a strong control over treeline in the western United States we conducted a growth chamber and field experiment that manipulated water availability and monitored photosynthesis, non-‐structural carbohydrates, growth, and survivorship in Picea engelmannii seedlings.
- In our growth chamber study we found an interaction between watering frequency and nighttime temperatures, with frequently watered, cool night trees growing more than infrequently watered trees grown with elevated nighttime temperatures. In the field experiment, survivorship increased from the driest to the wettest conditions while the timing of precipitation did not explain differences in survival. However, we found that large, infrequent rain events increased maximum photosynthetic rates compared to frequent, small rain events.
- Our results highlight the potential role of growing season water availability in limiting treeline expansion below the thermal limits of Picea engelmannii. As a consequence, the movement of treeline in this region in response to climate change is likely to be episodic and driven by multi-‐year periods of high water availability and frequency that overcome drought limitations.
Description of how the budget was spent
| Student Salary | Graduate Students | $3500 |
| Undergraduate Students | $12,500 | |
| Travel | Field Studies | $3,000 |
| Equipment | $1,500 | |
| Total | $20,000 |